List of menu IDs for Fancy Main Menu

Vanilla:

Main Menu:
net.minecraft.client.gui.GuiMainMenu

World Select (Singleplayer Worlds):
net.minecraft.client.gui.GuiWorldSelection

Multiplayer (Server List):
net.minecraft.client.gui.GuiMultiplayer

Options:
net.minecraft.client.gui.GuiOptions

Mod List:
net.minecraftforge.fml.client.GuiModList

Add Server:
net.minecraft.client.gui.GuiScreenAddServer

Direct Connect:
net.minecraft.client.gui.GuiScreenServerList

Custom:

Information & Resources:
rotn.client.gui.GuiInfoResources

Work In Progress:
rotn.client.gui.GuiWIP

Supporters:
rotn.client.gui.GuiSupporters

Credits:
rotn.client.gui.GuiCredits